CHAPTER VIII 

 THE CEREBRAL HEMISPHERES 



// is the long serial reactions of the ''distance receptors*' 

 that allow most scope for the selection of those brute organisms 

 that are fittest for survival in respect to elements of mind. The 

 "distance receptors" hence contribute most to the uprearing of 



the cerebrum. 



— C. S. Sherrington 



IN the walls of the forebrain of lower vertebrates 

 it is possible to chart with tolerable precision 

 the arrangements and boundaries of the various 

 regions within which are the mechanisms by which 

 most of the larger groups of reflex correlation are 

 effected. Some of the necessary data have been estab- 

 lished by direct physiological experiment. Others are 

 deductions from the known anatomical connections 

 of the parts. The second method is not so convincing 

 as the first, and yet when properly controlled it is very 

 dependable. 



The functions of the peripheral end-organs and 

 their nerves and of the primary cerebral sensory and 

 motor centers of these nerves are easily accessible to 

 direct experimental study, and they are well known. 

 In so far as these centers are connected with one 

 another and with other parts of the brain by anatomi- 

 cally well-defined fiber tracts, the functions of these 

 tracts and of the higher centers of correlation into 



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